Autonomous hydraulic jack



Filed Dec. 8. 1959 3 Sheets-Sheet 1 INVENTOR RENE Lac/EN y 1, 1962 R. LUCIEN 3,031,847

AUTONOMOUS HYDRAULIC JACK Filed Dec. 8, 1959 3 Sheets-Sheet 2 4 INVENTOR RENZ LUC/EN May 1, 1962 R. LUClEN AUTONOMOUS HYDRAULIC JACK 3 Sheets-Sheet 3 Filed Dec. 8, 1959 III M M 0 M W M 0 W M M 0 I I I u I INVENTOR RENE LUC/EN lllgll z M 0 M M n I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I n W n United States PatentOfifice Patented May 1, 1962 3,031,847 AUTONOMOUS HYDRAULIC JACK Rene Lucien, Neuilly-sur-Seine, France, assignor to Societe a Responsabilite Limitee: Recherches Etudes Production R.E.P., Paris, France, a corporation of France Filed Dec. 8, 1959, Ser. No. 858,111 Claims priority, application France Dec. 8, 1958 9 Claims. ((11. 60-52) This invention relates to hydraulic jacks and the like.

The invention contemplates the provision of a movement of translation initiated by means of electrical energy but effected by means of hydraulic energy since a fully electric arrangement, which, for example, consists of the use of a motor followed by a reducing gear and a device for converting rotation into a longitudinal movement, has the following drawbacks:

Complexity which is progressively greater as the speed I to be obtained is lower;

Lack of precision owing to the time-constant of the stopping, this being all the more marked as the speed to be obtained is higher;

Inevitable play in the gearing;

High cost in addition to the complexity of the device.

The present invention has as an object the provision of a device which, by simple means, converts electrical energy into hydraulic energy.

A further object of the present invention is to control the movement of translation obtained, in a precise manner and in both direction.

Yet another object of the invention is to facilitate obtaining the desired characteristics of efiort, speed and travel.

Further objects of the invention together with its advantages will be set forth during the course of the description which follows below, the said description being given in conjunction with the accompanying drawings in which:

FIG. 1 shows diagrammatically the complete assembly of an autonomous jack with a hydraulic generator, a distributor and an electromagnetic responsive device in accordance with the present invention;

FIG. 2 shows diagrammatically another arrangement of the distributor;

FIG. 3 shows diagrammatically a further arrangement of the complete assembly of the autonomous jack and additionally, a return accumulator; and

FIG. 4 is an enlarged view in detail of a portion of FIG. 3.

In FIG. 1, a generator of hydraulic energy is constituted by a polarized electro-magnetic circuit 1 (of the torque motor type) by means of which a sinusoidal movement of translation of a magnetic mass 3 may be obtained from alternating current supplied by a source 2. To this mass are coupled two pistons 101 and '201 which, by virtue of suitable ports 102 and 202 and clapper valves 103 and 203, suck hydraulic fluid from a chamber 4 in which the said pistons are immersed and pump fluid into the conduits 104 and 204.

It is to be noted that the use of a polarized electromagnetic circuit as compared with a non-polarized circuit (such as an electro-magnet of the usual type with a plunger core) has the following advantage: the alternating movement of the pistons takes place at the same frequency as the operating current (instead of taking place at twice this frequency) and in such manner as to provide a more favorable operation of the pistons.

The distribution is effected through the conduits 104 205 of a jack 5.

In each of conduits 104 and 204, a clapper valve 106 or 206 enables:

When open, the free return of the pumped liquid into the chamber 4.

When closed, delivery under pressure towards the corresponding chamber of the jack 5.

These clapper valves 106 and 206 are in. turn controlled by an electro-magnetic circuit 6 which can operate either with direct current or alternating current.

When supplied with direct current, this circuit will be of the type that is polarized by a permanent magnet 7. According to the direction of the direct current applied to the coil 8 by a signal 9, the mass 10 moves in one direction or in the other, thus causing one of the two clapper valves 106 or 206 to close under the action of associated valve spring. Movement of the jack is thus produced either in one direction or the other. In the absence of any operating current in the coil 8, the mass 10 is motionless and the clapper valves 106 and 206 are open in opposition to the effort of their respective springs.

In the case of operation of the circuit 6 with alternating current, it is possible to obtain the same results as above by applying this alternating control current to the coil 8 (without demodulating this current). In this arrangement there is substituted for the permanent magnet which polarizes the circuit, a coil 11 having a core 7 which coil is supplied with alternating current having the same frequency which will constitute a phase reference. According to the phase of the control current, the two currents will be in phase or out of phase. The combination of the two alternating fluxes thus produced will have the result of causing the displacement of the mass 10 in one direction or in the other. When no current is present in the coil 8, the mass 10 is subjected to no force whatever, even if the alternating current of reference is still flowing in the coil 11 and the clapper valves 106 and 206 remain open against the action of their respective springs.

The device which characterizes the present invention can be applied in particular to a servo-control mechanism.

In this case, it is an advantage to couple an electromagnetic responsive device to the jack 5.

This electromagnetic responsive device can be constructed in the following manner:

A coil unit 12, mounted on a core carried by the rod of the jack, is supplied with alternating current from a source 13 and produces a flux in the magnetic circuit 14. Two coils 107 and 207 are mounted in opposition and symmetrically in this magnetic circuit. When the coil 12 is in the center of the circuit-that is to say when the rod of the jack has completed half its length of travel-the two fluxes produced in the coils 107 and 207 are equal in absolute value, and their resultant is nil.

If the coil 12 which is driven by the rod is displaced, the reluctance of the circuit increases with respect to the path of one flux and decreases in the case of the other. There results the appearance, at the terminals 108 and 208 which are common to the coils 107 and 207, of an induced alternating voltage, having a phase which is variable according to the direction of displacement and an amplitude which is proportional to the said displacement.

In order that the differential variation of reluctance may be adequate, the portion of the circuit in front of which the displacement of the coil 12 takes place should be constituted by materials selected and arranged so as to obtain a relative permeability of value between that of air and that of iron, that is to say, of the order of 200 or 300, for example.

Again, in the case of the application of the present invention to a servo-control system, the control signal arrives simultaneously at the coil 8 which determines the direction of displacement, and at a relay 15 which, when in the closed position, starts up the generator 1. The said generator 1 can thus be allowed to operate continuously.

FIG, 2 illustrates an alternative form of the invention, without incorporating the hydraulic energy generator as shown in FIG. 1, comprising a separate pump 1 which supplies the jack with fluid under pressure. The fluid is returned to the chamber 4'. In FIG. 2, the elements which correspond to those of FIG. 1 retain the same reference numbers.

The distributor is similar to that described with referenceto FIG. 1, but it comprises two moving masses 10 and 16. The moving mass 10 actuates the exhaust valves 106 and 206 and the moving mass 16 actuates the admission valves 109 and 209 in a symmetrical manner, that is to say, the displacements of the moving masses 10 and 16 are of equal extent but of opposite direction, in such manner as to put simultaneously one of the chambers 105 or 205 of the jack into communication with the admission and the other chamber with exhaust. In addition, the exhaust valves 106 and 206 are slightly open in the neutral position to prevent any accidental leakage in the admission valves 109 and 209 from causing an untimely displacement of the jack 5 in the absence of the signal from source 9.

In the present invention, it is especially intended that the ball-valves as illustrated and described with reference to FIGS. 1 and 2 can be replaced by a distributor of the slide-valve type or by conical type valves.

FIGS. 3 and 4 illustrate an alternative embodiment of the. invention. In FIGS. 3 and 4, the elements corresponding to those of FIG. I retain the same reference numbers. The exhaust valves are each constituted by a ball 106 and 206 operated by a push-rod 110 and 210 actuated by a solenoid 111 and 211. When the solenoid 111, for example, is energized, it displaces the ball 106 from its seating and thus connects the chamber 105 and the jack 5 to exhaust. When there is no voltage applied to the solenoid 111, the ball 106 is seated and the chamber 105 is placed under pressure. In the absence of voltage on the two solenoids 111 and 211, the two chambers 105 and 205 are closed by the balls 106 and 206, which are seated due to the action of springs S1 and S2, and thus a complete absence of current locks the jack 5 in fixed position, even if the jack 5 is subjected to a force which would otherwise displace it. In normal operation, only one of the solenoids is energized such as, for example, solenoid 111, by which evacuation of the chamber 105 is effected, while the chamber 205 is under pressure. As a result the jack 5 moves upwardly.

In order to avoid the effect of an overpressure in a chamber of the jack 5, such as the chamber 105 for example, the seating 112 of the ball 106 is made to be movable in its housing. The said seating is held in its normal position by a. spring 113. If the pressure in the chamber 105 exceeds a pre-determined value, its action on the seating 112 overrides that of the spring 113, and the seating 112 moves towards the left, while the ball 106 is retained by its push-rod 110. The chamber 105 is thus connected to exhaust. This arrangement is that shown. for the clapper-valve 106 of FIG. 1. It is obvious that the same arrangement can be applied to the. other clapper valve 206.

For certain applications it is desirable or necessary that, in the case of absence of current, the jack 5 proceeds to the end of its travel in one direction. In this case one of the clapper valves 106 or 206 is modified and a hydraulic accumulator is added to the system. FIGS. 3 and 4 correspond to the case in which the jack 5 is intended to return to its bottom position when the current is not present. In this case, it is the clapper valve 206 which is modified in the following manner: the seating 212 of the said clapper-valve 206 is actuated by a solenoid 214 comprising a fixed armature 215 and a movable armature 216. When the solenoid 214 is excited, its moving armature 216 is attracted towards the right and holds the seating 212 of the clapper valve 206 on the right hand side. When no current is present, the pressure in the chamber 205 of the jack 5 forces the seating 212 and the armature 216 towards the left, while the ball 206 is held in position by its push-rod 210. The chamber 205 is thus connected to exhaust.

On the other hand an accumulator 18 (delimited in chain-dotted lines in FIG. 3) supplies, again in the case of absence of current, the chamber of the jack 5. This accumulator 18 is composed of a cylinder 19, the piston 20 of which is actuated by a spring 21. In normal service, the spring 21 is under compression, but the piston 20 is retained by a member 22 which is in turn held in position by an electro-magnet 23 despite the action of a restoring spring 24. In the case of absence of current, the electro-magnet 23 releases the member 22, which pivots under the action of its spring 24 and frees the piston 20. The spring 21 lowers the piston 20 and the cylinder 19 supplies the chamber 105. Since, as has already been seen, the chamber 205 is connected to exhaust, the jack 5 falls to the bottom of its travel.

In accordance with the invention, the accumulator is interlocked and the motor of the jack 5 does not have to overcome the force of the energizing spring 21 of the accumulator 13, which would otherwise make it necessary to provide a motor of unduly large size. Further, the maintenance of the position of the jack 5 is not likely to be impaired by an efiect of which results from a deviation under the permanent action of the said spring 21.

It is obviously preferable to provide for the supply in series of both the electro-magnets 23 and 214 in such manner that, in the case of absence of current, they act simultaneously. When the jack is put back into service, the re-establishment of the current supply and the sending of the control signal suflice to produce the filling of the cylinder 19, the piston 20 of which is locked automatically at the end of its travel by means of the member 22. An improvement in the clapper valve 206 with the solenoid 214 consists in providing the mobile armature 2160f this latter with a light return spring 217 which returns the moving armature 216 to its normal position as soon as the jack 5 has arrived at the end of its travel.

It should be noted that the jack 5 can be fitted with the electromagnetic device described in connection with FIG. 1, or with any other equivalent device.

What is claimed is:

'1. An autonomous hydraulic jack comprising a source of electrical energy adapted for producing alternating current energy, an electrically-operated generator of hy draulic energy having a fluid chamber for supplying fluid therefrom and including a pump of the torque-motor type and a magnetic circuit, said magnetic circuit including a permanent magnet and a coil electromagnetically coupled thereto and responsive to the alternating current energy from said source of electrical energy; a double-acting jack member having two chambers in fluid communication with said generato two intake clapper valves each having a fluid intake port, one of said valves being coupled between said fluid chamber and one of said jack chambers for supplying said fluid thereto and the other of said valves being coupled between said fluid chamber and the other of said jack chambers for supplying said fluid thereto, the fluid being supplied through the respective ports in said valves; a first movable mass operatively associated with said valves for actuation thereof to permit the fluid to pass therethrough into said jack chambers; a pair of pistons rigidly coupled to said first movable mass, said coil being excited by the alternating current energy for imparting a sinusoidal translation to said first movable mass thereby rigidly driving said two pistons; two exhaust clapper valves, one of said exhaust valves being coupled between said fluid chamber and one of said jack chambers and the other of said exhaust valves being coupled between said fluid chamber and the other of said jack chambers; a second movable mass coupled to said exhaust valves for the actuation thereof to permit the fluid to pass therethrough from said jack chambers into said fluid chamber, and a distributor for controlling the movement of said exhaust valves; and a hydraulic return accumulator coupled to one of said fluid chambers and including a piston in said accumulator and defining a chamber therein for fluid, a spring maintained under compression by the latter said piston, and fluid pressure thereagainst, and an electromagnet for selectively locking said piston against movement.

2. A jack as claimed in claim 1, including a solenoid magnetically associated with at least one of said exhaust valves, said solenoid being adapted for opening said lastmentioned exhaust valve.

3. A jack as claimed in claim 1 including a movable seating for at least one of said exhaust valves, a spring holding said seating in a normal position to maintain said last-mentioned valve closed, said movable seating being displaced by pressure in the associated fluid chamber exceeding a determinable value to open said last-mentioned valve.

4. A jack as claimed in claim 1, including a movable seating for at least one of said exhaust valves and a solenoid for holding said seating in position to close said last-mentioned valve and for moving said seating away from the latter said position to open said last-mentioned valve.

5. A jack as claimed in claim 4, including a spring for restoring said seating to the latter said position in the absence of pressure.

6. A jack as claimed in claim 1, in which said second movable mass includes a pair of push rods and said exhaust valves include a ball actuated by a respective one of said push rods to open said exhaust valves.

7. A jack as claimed in claim 6, including means to lock said jack member in position, said means comprising a solenoid for each said push rods, and a spring for each said balls for maintenance thereof in engagement with said push rods and to seal said exhaust valves, said solenoids being effective to overcome the force of said springs for displacing said push rods and moving said balls to open said exhaust valves, said solenoids being further adapted for cooperating with said springs to prevent removal of the fluid from said jack chambers thereby locking said jack member in position against the fluid.

8. A jack as claimed in claim 7, including a solenoid device, a fixed armature coupled with one of said push rods and a movable armature, a valve seating movably coupled to said one push rod and movable with said movable armature, said solenoid member being elfective to overcome the force of one of said springs to open said associated exhaust valve to remove the fluid from one of said jack chambers.

9. A jack as claimed in claim 8, including a spring coupled to said movable armature for restoration thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,283,886 Henkell May 19, 1942 2,398,421 Frische et a1. Apr. 16, 1946 2,573,993 Sedgwick Nov. 6, 1951 2,751,753 Ray June 26, 1956 

